Q: This problem is about non-inertial frames. In the standard version the inclined plane is fixed to the ground and it does not move. In this version, the wedge can - and it will - move as the object descends. Recall how you solved the problem in your introductory physics course and change the solution to solve this modified version. No new knowledge is necessary; you could have solved this problem in that course.
A wedge of mass M and angle ? is placed on a flat frictionless surface. A crate of mass m is placed on the wedge at height h and starts sliding down the wedge without friction. Find the acceleration of the crate and the wedge relative to the ground. How long does it take for the crate to reach the bottom of the wedge?